update in material and process technologies for 2.5/3d ic global summit 3dic... · e.g. cost of...

Update in Material and Process Technologies for 2.5/3D IC Dr. Rainer Knippelmeyer CTO and VP of R&D, SUSS Microtec AG

Update in Material and Process Technologies for 2.5/3D IC

Rainer Knippelmeyer, SUSS Microtec AG

Temporary Bonding / Debonding as Thin Wafer Handling Solution for 3DIC & Interposers

Device Manufacturing

TSV Processing Temp

Bonding Thinning Post Processing Temp Debonding

Stacking C2C C2W W2W

Thin

Wafer Handling



Status of Temporary Bonding/Debonding Processes and Materials

Initial R&D

Volume Ramp-up

HVM Line R&D

(Integration)

Industry

Feasibility Yield (Cost) Improvement



Outline

Latest Insights in Material and Process Technologies for

Interposer and 3D Stacking

4

Introduction: Room Temperature Debonding

Material/Process Optimization & Survey

1

2

Conclusions & Roadmap 3



DEBOND METHOD / MATERIAL

SOLVENT RELEASE

THERMAL SLIDE SOLID

STATE LASER RELEASE

MECHANICAL EXCIMER

LASER ASSISTED

SIMPLE CARRIER LOW COO

NO THERMAL STRESSES NO CARBONIZATION

HIGH THROUGHPUT CAPABLE

ROOM TEMPERATURE DEBONDING

SUSS FOCUS

Industry Trend Towards Room Temperature Debonding



Device Wafer

Add & Prepare

Release or Zoned Layer(s)

Thinned Device

Wafer

Carrier Wafer Attach to Dicing Frame

(optional edge cut / for

ZoneBond® )

Mechanical Debond at

Room Temperature

Clean Device Wafer

Flip Wafer

Bond

Flip Wafer

Temporary Bond

Debond

Carrier Wafer

Spin Coat & Prepare

Adhesive(s)

General Mechanical Room Temperature Debond Process



Excimer Laser Assisted

Room Temperature Debonding

• Excimer laser debonding Mechanism

– Nanosecond laser pulses break bonds of polymer materials and create gaseous state

– Fast expansion of gas “cuts” material open

• Advantages to Solid State Laser

– No carbonization / thermal stresses

• Flat top beam profile / 10x better stability

no excess energy in substrate

– No laser energy near device

• Laser light absorbed in 200-300 nm layer

– Allows unobscured visible light inspection

• Adhesive only has to absorb in UV (308/248 nm)

– Works on a range of existing adhesives

Device Wafer

Glas Carrier

Laser beam

Adhesive

Absorption

layer

absorption in thin special layer

absorption in first 200-300 nm of adhesive

Device Wafer

Glas Carrier

Adhesive

Glas carrier and wafer separated



Device Wafer

Add & Prepare

ABSORPTION LAYER

Thinned Device

Wafer

Carrier Wafer Attach to Dicing

Frame

Mechanical Debond /

(Minimal/Zero lift of force)

at Room Temperature

Clean Device Wafer

Flip Wafer

Bond

Flip Wafer

Temporary Bond

Debond

Carrier Wafer

Spin Coat & Prepare

Adhesive(s)

General Laser Assisted Room Temperature Debond Process

Excimer Laser

Treatment (308nm)

( ) Optional



Outline



9



1

2




• Vacuum process compatibility

• Temperature stability ≥ 250C (up to 350C)

• Chemical compatibility

General Adhesive Requirements for Temporary Bonding/Debonding

Application Type of Topography Embedded in Adhesive Adhesive Thickness

Today’s Si TTV Requirements

Thinning / TSV exposure

Pad / RDL 20µm ≤2µm

Chip stacking / Interposer

Cu Nail / Micro Bump (10 - 40µm) 20 - 70µm ≤4µm

Interposer C4 bump (70-80µm) ≥100µm ≤5-7µm

Device Manufacturing

TSV Processing Temp

Bonding Thinning Post Processing Temp Debonding

Stacking C2C C2W W2W

• Easy to de-bond (no thermal stress)

• Easy to clean (no chemical stress)

• Possibility to re-use / recycle carriers

• Total Thickness Variation on Silicon



Temp. Bonding/Debonding Process Survey

11

Production Readiness

1 : Qualified /used for high volume manufacturing

2: Integration tests in line at institute

3: Qualified by SUSS internal tests

Cost of Ownership

Equipment cost

Process times & cycles

Other consumables:

e.g. Cost of Tape

(Cost of materials)

Performance

Process Latitude

(Survivability / Debondability)

Achievable min. wafer thickness (TTV)

WaferBOND™

ZoneBOND® WSS

“laser free”



WaferBOND

™ ZoneBOND

®

WSS

“laser

free”

Other Material Suppliers

Different material classes: • Thermoplastic • Thermoset • Photoset

SUSS Open Equipment Platform and Supported Materials

10 Material suppliers & processes: 9 enable mechanical Debonding 4 enable Laser Asstisted Room Temp. Debonding



TTV improvement from 10-15µm down to 2µm for C4 bumped wafers with 70µm bump height and 115µm adhesive thickness

TTV Optimization Example with Thin Materials (TMAT) Adhesive

Before process optimization: bonded stack TTV =10-15µm

After process optimization: bonded stack TTV = 2µm

Adhesive Carrier

Device Bonded stack TTV



Scanning Acoustic Microscope Images after Bonding and Thinning

SAM image post bond (full

thickness) shows no voids SAM image after thinning

to 50µm shows no defects

•300mm wafers with 8µm bumps, 60µm adhesive

•Si - TTV = 1.3 µm after thinning to 50µm



Cost of Ownership: Optimization of Cleaning Procedures

Solvent Compability

Influencing Parameters

Process Steps

Nozzle

Flow Rate

Solvent

Dispense Spin Off Rinse Dry

Nozzle

Flow Rate

Time / Spin Speed / Puddle

Time

Spin Speed

Time

Spin Speed

Time

Spin Speed

Number of cycles

Solves Adhesive

Tape Frame

Wafer

Chemical #1 Chemical #2 Chemical #3 Chemical #4



Cost of Ownership: Example for 8x Improvement of Cleaning CoO

Solvent Glue thickness Cleaning time Consumption of

the solvent

Origin POR

110 µm 100% 100%

Improved POR

110 µm 72% 66%

Comparison of the cleaning time and solvent consumption

Solvent Price per liter Consumption of the solvent

Volume Costs

Origin POR

100% 100% 100% €

Improved POR

30% 66% 12,5%€

Comparison of the solvent consumption and the costs

8 1,5



Dicing tape integrity critical for results Special resistant tapes increase CoO

Wrinkled tape increases the risk of thin wafer damage during handling

Solvent exposure can lead to substantial tape degradation



Cost of Ownership reduction: Tape protection allows to use standard tapes for most cleaning chemicals

SUSS thin wafer cleaning module allows to protect the tape and frame

•Good chance to use existing and qualified tapes (cost benefit)

•Higher flexibility for cleaning solvents



20

Optimization / Collaboration results:

• Adhesive

• stable at high postprocessing temperatures > 350°C

• Based on mature temporary bonding material composition

• Transparent adhesive allowing optical inspection

• Throughput: > 40wph

• Debonding time < 45sec for 300mm wafer (160mJ/cm2)

High temperature / High Throughput low CoO capable laser assisted debonding

Wafer stack after excimer laser debonding Wafer stack with glass carrier removed Wafer after Cleaning

In collaboration with



Succesfull process flow integration results at IMEC

Device

Carrier

Device

TTV of 50µm Si wafer

Carrier

Thinned Device Wafer

Temp. Bond Adhesive

Adhesive Thickness TTV after thinning

on 50µm Si

TTV[%] as a function of Adh.

Thickness

A 55µm 3µm 5,5%

A 20µm 2µm 10%

B 100µm 7µm 7%

C 45µm 4µm 8,9%

D 50µm 2µm 4,0%

E 60µm 5µm 8,3%



Outline



22



1

2




0

20

40

60

80

100

Material "A"High Bond

Force

Material "B"High Latitude

ComplexProcess

Material "A"Lower Bond

Force

Material "B"Mechanical

Ideal ProcessFlow

Material "C"Mechanical

Material "C"High Latitude

Material "F"Mechanical

Examples of cost equipment / Maturity for 2.5D / 3D processes

No

rma

lize

d C

ost of E

qu

ipm

en

t / W

afe

r

Cost of Equipment includes: Bonder / Debonder / Device Wafer Cleaner, Carrier cleaning / recycling is not considered

Maturity Qualified or in Production / Process Integration at Institutes / Customer Samples Internal Qual.



Laser Assisted Debonding vs. Mechanical Debonding

REQUIREMENT MECHANICAL EXCIMER

LASER ASSISTED

DUAL CARRIER PROCESS FLOW (SELECTIVE DEBONDING) *

GLAS CARRIER

SILICON CARRIER

RISK OF LASER ENERGY NEAR ACTIVE DEVICE **

3D

´Memory

Logic

2.5D

Interposer

* Limited Process window/latitude ** Risk can be significantly reduced by proper choice of adhesive/absorption layer

• Both processes suited to 3D and 2.5D requirements • Mechanical debonding seems closest fit to 3D requirements • Laser assisted process originally used only for high performance logic –

now seems closest fit to 2.5D interposer requirements

ROOM TEMP. DEBONDING



Roadmap: Drivers & Levers

•Choice of Materials

•Material Consumption

•Process Timing and flow

•Equipment optimization

•Bump size and density

•Final device wafer thickness

•Temperature and chemical load

Close collaborations and JDPs with: • Institutes,

•Adhesive and tape manufacturers

•Further TTV Optimization

•Extend room temp. debonding

•New/Improved bond materials

• Leading edge customers



Roadmap: SUSS/ITRI: 5µm Ultra Thin Wafer

300mm 50µm thickness with TSV wafer

SUSS XBS300 5µm Ultra Thin Wafer



• Trend towards room temperature debonding

–Mechanical debonding mainly 3D processes

–Laser assisted debonding mostly 2.5 D processes

• 10 materials/processes available for room temperature debonding

–4 in or qualified for Volume Manufacturing

–1.5 – 3 x Cost of Equipment reductions in nearterm roadmap

–Main optimization topic: process latitude

• Close collaborations enable roadmap

–Equipment vendors, material vendors

–Leading customers, institutes

Summary

See you next time at:

SUSS TECHNOLOGY FORUM

ASIA 2013

Taiwan, Hsinchu | November 13

China, Shanghai | November 15

Korea November 19

update in material and process technologies for 2.5/3d ic global summit 3dic... · e.g. cost of...

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